/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package support.ui.utilities.time;

import java.text.DateFormat;
import java.text.FieldPosition;
import java.text.Format;
import java.text.ParseException;
import java.text.ParsePosition;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;

/**
 * <p>FastDateFormat is a fast and thread-safe version of
 * {@link java.text.SimpleDateFormat}.</p>
 *
 * <p>This class can be used as a direct replacement to
 * {@code SimpleDateFormat} in most formatting and parsing situations.
 * This class is especially useful in multi-threaded server environments.
 * {@code SimpleDateFormat} is not thread-safe in any JDK version,
 * nor will it be as Sun have closed the bug/RFE.
 * </p>
 *
 * <p>All patterns are compatible with
 * SimpleDateFormat (except time zones and some year patterns - see below).</p>
 *
 * <p>Since 3.2, FastDateFormat supports parsing as well as printing.</p>
 *
 * <p>Java 1.4 introduced a new pattern letter, {@code 'Z'}, to represent
 * time zones in RFC822 format (eg. {@code +0800} or {@code -1100}).
 * This pattern letter can be used here (on all JDK versions).</p>
 *
 * <p>In addition, the pattern {@code 'ZZ'} has been made to represent
 * ISO8601 full format time zones (eg. {@code +08:00} or {@code -11:00}).
 * This introduces a minor incompatibility with Java 1.4, but at a gain of
 * useful functionality.</p>
 *
 * <p>Javadoc cites for the year pattern: <i>For formatting, if the number of
 * pattern letters is 2, the year is truncated to 2 digits; otherwise it is
 * interpreted as a number.</i> Starting with Java 1.7 a pattern of 'Y' or
 * 'YYY' will be formatted as '2003', while it was '03' in former Java
 * versions. FastDateFormat implements the behavior of Java 7.</p>
 *
 * @since 2.0
 * @version $Id: FastDateFormat.java 1572877 2014-02-28 08:42:25Z britter $
 */
public class FastDateFormat extends Format implements DateParser, DatePrinter {
  /**
   * Required for serialization support.
   *
   * @see java.io.Serializable
   */
  private static final long serialVersionUID = 2L;

  /**
   * FULL locale dependent date or time style.
   */
  public static final int FULL = DateFormat.FULL;
  /**
   * LONG locale dependent date or time style.
   */
  public static final int LONG = DateFormat.LONG;
  /**
   * MEDIUM locale dependent date or time style.
   */
  public static final int MEDIUM = DateFormat.MEDIUM;
  /**
   * SHORT locale dependent date or time style.
   */
  public static final int SHORT = DateFormat.SHORT;

  private static final FormatCache<FastDateFormat> cache = new FormatCache<FastDateFormat>() {
    @Override
    protected FastDateFormat createInstance(final String pattern, final TimeZone timeZone, final Locale locale) {
      return new FastDateFormat(pattern, timeZone, locale);
    }
  };

  private final FastDatePrinter printer;
  private final FastDateParser parser;

  //-----------------------------------------------------------------------

  /**
   * <p>Gets a formatter instance using the default pattern in the
   * default locale.</p>
   *
   * @return a date/time formatter
   */
  public static FastDateFormat getInstance() {
    return cache.getInstance();
  }

  /**
   * <p>Gets a formatter instance using the specified pattern in the
   * default locale.</p>
   *
   * @param pattern {@link java.text.SimpleDateFormat} compatible
   *                pattern
   * @return a pattern based date/time formatter
   * @throws IllegalArgumentException if pattern is invalid
   */
  public static FastDateFormat getInstance(final String pattern) {
    return cache.getInstance(pattern, null, null);
  }

  /**
   * <p>Gets a formatter instance using the specified pattern and
   * time zone.</p>
   *
   * @param pattern  {@link java.text.SimpleDateFormat} compatible
   *                 pattern
   * @param timeZone optional time zone, overrides time zone of
   *                 formatted date
   * @return a pattern based date/time formatter
   * @throws IllegalArgumentException if pattern is invalid
   */
  public static FastDateFormat getInstance(final String pattern, final TimeZone timeZone) {
    return cache.getInstance(pattern, timeZone, null);
  }

  /**
   * <p>Gets a formatter instance using the specified pattern and
   * locale.</p>
   *
   * @param pattern {@link java.text.SimpleDateFormat} compatible
   *                pattern
   * @param locale  optional locale, overrides system locale
   * @return a pattern based date/time formatter
   * @throws IllegalArgumentException if pattern is invalid
   */
  public static FastDateFormat getInstance(final String pattern, final Locale locale) {
    return cache.getInstance(pattern, null, locale);
  }

  /**
   * <p>Gets a formatter instance using the specified pattern, time zone
   * and locale.</p>
   *
   * @param pattern  {@link java.text.SimpleDateFormat} compatible
   *                 pattern
   * @param timeZone optional time zone, overrides time zone of
   *                 formatted date
   * @param locale   optional locale, overrides system locale
   * @return a pattern based date/time formatter
   * @throws IllegalArgumentException if pattern is invalid
   *                                  or {@code null}
   */
  public static FastDateFormat getInstance(final String pattern, final TimeZone timeZone, final Locale locale) {
    return cache.getInstance(pattern, timeZone, locale);
  }

  //-----------------------------------------------------------------------

  /**
   * <p>Gets a date formatter instance using the specified style in the
   * default time zone and locale.</p>
   *
   * @param style date style: FULL, LONG, MEDIUM, or SHORT
   * @return a localized standard date formatter
   * @throws IllegalArgumentException if the Locale has no date
   *                                  pattern defined
   * @since 2.1
   */
  public static FastDateFormat getDateInstance(final int style) {
    return cache.getDateInstance(style, null, null);
  }

  /**
   * <p>Gets a date formatter instance using the specified style and
   * locale in the default time zone.</p>
   *
   * @param style  date style: FULL, LONG, MEDIUM, or SHORT
   * @param locale optional locale, overrides system locale
   * @return a localized standard date formatter
   * @throws IllegalArgumentException if the Locale has no date
   *                                  pattern defined
   * @since 2.1
   */
  public static FastDateFormat getDateInstance(final int style, final Locale locale) {
    return cache.getDateInstance(style, null, locale);
  }

  /**
   * <p>Gets a date formatter instance using the specified style and
   * time zone in the default locale.</p>
   *
   * @param style    date style: FULL, LONG, MEDIUM, or SHORT
   * @param timeZone optional time zone, overrides time zone of
   *                 formatted date
   * @return a localized standard date formatter
   * @throws IllegalArgumentException if the Locale has no date
   *                                  pattern defined
   * @since 2.1
   */
  public static FastDateFormat getDateInstance(final int style, final TimeZone timeZone) {
    return cache.getDateInstance(style, timeZone, null);
  }

  /**
   * <p>Gets a date formatter instance using the specified style, time
   * zone and locale.</p>
   *
   * @param style    date style: FULL, LONG, MEDIUM, or SHORT
   * @param timeZone optional time zone, overrides time zone of
   *                 formatted date
   * @param locale   optional locale, overrides system locale
   * @return a localized standard date formatter
   * @throws IllegalArgumentException if the Locale has no date
   *                                  pattern defined
   */
  public static FastDateFormat getDateInstance(final int style, final TimeZone timeZone, final Locale locale) {
    return cache.getDateInstance(style, timeZone, locale);
  }

  //-----------------------------------------------------------------------

  /**
   * <p>Gets a time formatter instance using the specified style in the
   * default time zone and locale.</p>
   *
   * @param style time style: FULL, LONG, MEDIUM, or SHORT
   * @return a localized standard time formatter
   * @throws IllegalArgumentException if the Locale has no time
   *                                  pattern defined
   * @since 2.1
   */
  public static FastDateFormat getTimeInstance(final int style) {
    return cache.getTimeInstance(style, null, null);
  }

  /**
   * <p>Gets a time formatter instance using the specified style and
   * locale in the default time zone.</p>
   *
   * @param style  time style: FULL, LONG, MEDIUM, or SHORT
   * @param locale optional locale, overrides system locale
   * @return a localized standard time formatter
   * @throws IllegalArgumentException if the Locale has no time
   *                                  pattern defined
   * @since 2.1
   */
  public static FastDateFormat getTimeInstance(final int style, final Locale locale) {
    return cache.getTimeInstance(style, null, locale);
  }

  /**
   * <p>Gets a time formatter instance using the specified style and
   * time zone in the default locale.</p>
   *
   * @param style    time style: FULL, LONG, MEDIUM, or SHORT
   * @param timeZone optional time zone, overrides time zone of
   *                 formatted time
   * @return a localized standard time formatter
   * @throws IllegalArgumentException if the Locale has no time
   *                                  pattern defined
   * @since 2.1
   */
  public static FastDateFormat getTimeInstance(final int style, final TimeZone timeZone) {
    return cache.getTimeInstance(style, timeZone, null);
  }

  /**
   * <p>Gets a time formatter instance using the specified style, time
   * zone and locale.</p>
   *
   * @param style    time style: FULL, LONG, MEDIUM, or SHORT
   * @param timeZone optional time zone, overrides time zone of
   *                 formatted time
   * @param locale   optional locale, overrides system locale
   * @return a localized standard time formatter
   * @throws IllegalArgumentException if the Locale has no time
   *                                  pattern defined
   */
  public static FastDateFormat getTimeInstance(final int style, final TimeZone timeZone, final Locale locale) {
    return cache.getTimeInstance(style, timeZone, locale);
  }

  //-----------------------------------------------------------------------

  /**
   * <p>Gets a date/time formatter instance using the specified style
   * in the default time zone and locale.</p>
   *
   * @param dateStyle date style: FULL, LONG, MEDIUM, or SHORT
   * @param timeStyle time style: FULL, LONG, MEDIUM, or SHORT
   * @return a localized standard date/time formatter
   * @throws IllegalArgumentException if the Locale has no date/time
   *                                  pattern defined
   * @since 2.1
   */
  public static FastDateFormat getDateTimeInstance(final int dateStyle, final int timeStyle) {
    return cache.getDateTimeInstance(dateStyle, timeStyle, null, null);
  }

  /**
   * <p>Gets a date/time formatter instance using the specified style and
   * locale in the default time zone.</p>
   *
   * @param dateStyle date style: FULL, LONG, MEDIUM, or SHORT
   * @param timeStyle time style: FULL, LONG, MEDIUM, or SHORT
   * @param locale    optional locale, overrides system locale
   * @return a localized standard date/time formatter
   * @throws IllegalArgumentException if the Locale has no date/time
   *                                  pattern defined
   * @since 2.1
   */
  public static FastDateFormat getDateTimeInstance(final int dateStyle, final int timeStyle, final Locale locale) {
    return cache.getDateTimeInstance(dateStyle, timeStyle, null, locale);
  }

  /**
   * <p>Gets a date/time formatter instance using the specified style and
   * time zone in the default locale.</p>
   *
   * @param dateStyle date style: FULL, LONG, MEDIUM, or SHORT
   * @param timeStyle time style: FULL, LONG, MEDIUM, or SHORT
   * @param timeZone  optional time zone, overrides time zone of
   *                  formatted date
   * @return a localized standard date/time formatter
   * @throws IllegalArgumentException if the Locale has no date/time
   *                                  pattern defined
   * @since 2.1
   */
  public static FastDateFormat getDateTimeInstance(final int dateStyle, final int timeStyle, final TimeZone timeZone) {
    return getDateTimeInstance(dateStyle, timeStyle, timeZone, null);
  }

  /**
   * <p>Gets a date/time formatter instance using the specified style,
   * time zone and locale.</p>
   *
   * @param dateStyle date style: FULL, LONG, MEDIUM, or SHORT
   * @param timeStyle time style: FULL, LONG, MEDIUM, or SHORT
   * @param timeZone  optional time zone, overrides time zone of
   *                  formatted date
   * @param locale    optional locale, overrides system locale
   * @return a localized standard date/time formatter
   * @throws IllegalArgumentException if the Locale has no date/time
   *                                  pattern defined
   */
  public static FastDateFormat getDateTimeInstance(
          final int dateStyle, final int timeStyle, final TimeZone timeZone, final Locale locale) {
    return cache.getDateTimeInstance(dateStyle, timeStyle, timeZone, locale);
  }

  // Constructor
  //-----------------------------------------------------------------------

  /**
   * <p>Constructs a new FastDateFormat.</p>
   *
   * @param pattern  {@link java.text.SimpleDateFormat} compatible pattern
   * @param timeZone non-null time zone to use
   * @param locale   non-null locale to use
   * @throws NullPointerException if pattern, timeZone, or locale is null.
   */
  protected FastDateFormat(final String pattern, final TimeZone timeZone, final Locale locale) {
    this(pattern, timeZone, locale, null);
  }

  // Constructor
  //-----------------------------------------------------------------------

  /**
   * <p>Constructs a new FastDateFormat.</p>
   *
   * @param pattern      {@link java.text.SimpleDateFormat} compatible pattern
   * @param timeZone     non-null time zone to use
   * @param locale       non-null locale to use
   * @param centuryStart The start of the 100 year period to use as the "default century" for 2 digit year parsing.  If centuryStart is null, defaults to now - 80 years
   * @throws NullPointerException if pattern, timeZone, or locale is null.
   */
  protected FastDateFormat(final String pattern, final TimeZone timeZone, final Locale locale, final Date centuryStart) {
    printer = new FastDatePrinter(pattern, timeZone, locale);
    parser = new FastDateParser(pattern, timeZone, locale, centuryStart);
  }

  // Format methods
  //-----------------------------------------------------------------------

  /**
   * <p>Formats a {@code Date}, {@code Calendar} or
   * {@code Long} (milliseconds) object.</p>
   *
   * @param obj        the object to format
   * @param toAppendTo the buffer to append to
   * @param pos        the position - ignored
   * @return the buffer passed in
   */
  @Override
  public StringBuffer format(final Object obj, final StringBuffer toAppendTo, final FieldPosition pos) {
    return printer.format(obj, toAppendTo, pos);
  }

  /**
   * <p>Formats a millisecond {@code long} value.</p>
   *
   * @param millis the millisecond value to format
   * @return the formatted string
   * @since 2.1
   */
  @Override
  public String format(final long millis) {
    return printer.format(millis);
  }

  /**
   * <p>Formats a {@code Date} object using a {@code GregorianCalendar}.</p>
   *
   * @param date the date to format
   * @return the formatted string
   */
  @Override
  public String format(final Date date) {
    return printer.format(date);
  }

  /**
   * <p>Formats a {@code Calendar} object.</p>
   *
   * @param calendar the calendar to format
   * @return the formatted string
   */
  @Override
  public String format(final Calendar calendar) {
    return printer.format(calendar);
  }

  /**
   * <p>Formats a millisecond {@code long} value into the
   * supplied {@code StringBuffer}.</p>
   *
   * @param millis the millisecond value to format
   * @param buf    the buffer to format into
   * @return the specified string buffer
   * @since 2.1
   */
  @Override
  public StringBuffer format(final long millis, final StringBuffer buf) {
    return printer.format(millis, buf);
  }

  /**
   * <p>Formats a {@code Date} object into the
   * supplied {@code StringBuffer} using a {@code GregorianCalendar}.</p>
   *
   * @param date the date to format
   * @param buf  the buffer to format into
   * @return the specified string buffer
   */
  @Override
  public StringBuffer format(final Date date, final StringBuffer buf) {
    return printer.format(date, buf);
  }

  /**
   * <p>Formats a {@code Calendar} object into the
   * supplied {@code StringBuffer}.</p>
   *
   * @param calendar the calendar to format
   * @param buf      the buffer to format into
   * @return the specified string buffer
   */
  @Override
  public StringBuffer format(final Calendar calendar, final StringBuffer buf) {
    return printer.format(calendar, buf);
  }

  // Parsing
  //-----------------------------------------------------------------------


  /* (non-Javadoc)
   * @see DateParser#parse(java.lang.String)
   */
  @Override
  public Date parse(final String source) throws ParseException {
    return parser.parse(source);
  }

  /* (non-Javadoc)
   * @see DateParser#parse(java.lang.String, java.text.ParsePosition)
   */
  @Override
  public Date parse(final String source, final ParsePosition pos) {
    return parser.parse(source, pos);
  }

  /* (non-Javadoc)
   * @see java.text.Format#parseObject(java.lang.String, java.text.ParsePosition)
   */
  @Override
  public Object parseObject(final String source, final ParsePosition pos) {
    return parser.parseObject(source, pos);
  }

  // Accessors
  //-----------------------------------------------------------------------

  /**
   * <p>Gets the pattern used by this formatter.</p>
   *
   * @return the pattern, {@link java.text.SimpleDateFormat} compatible
   */
  @Override
  public String getPattern() {
    return printer.getPattern();
  }

  /**
   * <p>Gets the time zone used by this formatter.</p>
   * <p/>
   * <p>This zone is always used for {@code Date} formatting. </p>
   *
   * @return the time zone
   */
  @Override
  public TimeZone getTimeZone() {
    return printer.getTimeZone();
  }

  /**
   * <p>Gets the locale used by this formatter.</p>
   *
   * @return the locale
   */
  @Override
  public Locale getLocale() {
    return printer.getLocale();
  }

  /**
   * <p>Gets an estimate for the maximum string length that the
   * formatter will produce.</p>
   * <p/>
   * <p>The actual formatted length will almost always be less than or
   * equal to this amount.</p>
   *
   * @return the maximum formatted length
   */
  public int getMaxLengthEstimate() {
    return printer.getMaxLengthEstimate();
  }

  // Basics
  //-----------------------------------------------------------------------

  /**
   * <p>Compares two objects for equality.</p>
   *
   * @param obj the object to compare to
   * @return {@code true} if equal
   */
  @Override
  public boolean equals(final Object obj) {
    if (!(obj instanceof FastDateFormat)) {
      return false;
    }
    final FastDateFormat other = (FastDateFormat) obj;
    // no need to check parser, as it has same invariants as printer
    return printer.equals(other.printer);
  }

  /**
   * <p>Returns a hashcode compatible with equals.</p>
   *
   * @return a hashcode compatible with equals
   */
  @Override
  public int hashCode() {
    return printer.hashCode();
  }

  /**
   * <p>Gets a debugging string version of this formatter.</p>
   *
   * @return a debugging string
   */
  @Override
  public String toString() {
    return "FastDateFormat[" + printer.getPattern() + "," + printer.getLocale() + "," + printer.getTimeZone().getID() + "]";
  }


  /**
   * <p>Performs the formatting by applying the rules to the
   * specified calendar.</p>
   *
   * @param calendar the calendar to format
   * @param buf      the buffer to format into
   * @return the specified string buffer
   */
  protected StringBuffer applyRules(final Calendar calendar, final StringBuffer buf) {
    return printer.applyRules(calendar, buf);
  }
}
